The present invention relates to an electronic device having a solar cell and a unit driven by a power generated by the solar cell and, more particularly, an electronic device which can be realized with various designs by using a transparent solar cell having thin-line-shaped photocells.
An electronic device having therein a solar cell and a unit which operates on the solar cell as a power source is well known.
Since a photocell for receiving light and generating a power in the solar cell is usually made of an opaque material such as a fuscous material, the solar cell cannot be provided on a digital display member and an analog display member.
Consequently, when the solar cell is mounted on an electronic device having the digital or analog display member, it has to be mounted by avoiding the display member. Due to this, the electronic device may look unattractive and, moreover, is limited in designing.
A technique of solving such a problem by using a transparent solar cell achieved by forming thin-line-shaped photocells at regular intervals on a transparent substrate is known by, for example, the publication of Japanese Utility Model Application Laid-Open No. 57-94964.
The solar cell disclosed in the publication is obtained by etching photocells to be sufficiently narrow on a transparent substrate so that the solar cell looks transparent within a visual range of a human.
In the electronic device disclosed in the publication, however, the solar cell is constructed by forming a single photocell in one stroke on a transparent substrate, so that the sufficient power necessary to operate the electronic device cannot be substantially obtained from the solar cell. The electronic device has not therefore been realized yet.
In recent years, skeleton products which are see-through are in fashion. A watch which looks more transparent is also in demand from a fashion viewpoint.
It is however difficult for a conventional watch using a solar cell to address the above-described demand for a reason of property that the solar cell is opaque and a reason of function that sufficient electromotive force cannot be obtained when an effective area of the solar cell is reduced.
Moreover, in the solar cell, photocells are constructed by stacking thin films of silicon or the like. Consequently, when static electricity of a few thousand volts (V) built up on a human body or the like is directly applied to the photocells, there is a fear such that a pin hole, burn, or the like occurs due to internal discharge and a circuit device is destroyed by short circuit.
The present invention has been achieved in consideration of the above problems. An object of the present invention is to provide an electronic device with largely improved flexibility in designing the electronic device to satisfy the user""s fashion mind by using a solar cell having improved transparency by making photocells extremely narrowed and capable of obtaining an electromotive force sufficient to operate the electronic device, and to provide a durable electronic device which is protected from external environments such as static electricity built on a human body or the like by forming a transparent electrode film on or near the surface of a photocell.
In order to solve the problems, according to the invention, in an electronic device having a solar cell and a unit driven by a power generated by the solar cell, the solar cell is a translucent solar cell including a transparent cell substrate; a plurality of conductive portions provided around the cell substrate and connected in series; and a plurality of photocells, each having a thin-line shape, formed at proper intervals on the cell substrate and connected to the conductive portions.
With the configuration, by forming the plurality of thin-line-shaped photocells on the cell substrate at proper intervals, the photocells are suppressed from being visually recognized, so that a transparent solar cell can be obtained. The intervals of the photocells are preferably regular intervals. With the configuration, a solar cell having higher transparency can be obtained.
Moreover, by connecting the plurality of conductive portions in series and connecting the photocells to the conductive portions, sufficient electromotive force necessary to operate the electronic device can be obtained.
The photocell having a thin-line shape is formed so as to extend from one of the conductive portions in a direction crossing the cell substrate, close to the other conductive portion, thereby limiting the portion in which no photocell is formed to an extremely small area in the periphery of the cell substrate. Thus, irregular color of the translucent solar cell can be lessened.
By using the translucent solar cell as described above, the solar cell can be disposed above the display member of the electronic device, so that the flexibility in designing can be increased.
The display member may be a liquid crystal display. The liquid crystal display may be provided on the back of the cell substrate or formed integrally with the translucent solar cell.
It is also possible to dispose the translucent solar cell on the upper side of a casing of the electronic device, dispose the unit driven by the power generated by the solar cell below the translucent solar cell in the casing, create a space between the unit and the casing, and dispose a transparent member under the electronic device, so that the electronic device is see-through.
In this case, the translucent solar cell may be also disposed on the lower side of the casing, or the translucent solar cell may be disposed only on the lower side of the casing.
By using the invention to a timepiece, the improved flexibility in designing the timepiece can be obtained.
The timepiece may be an analog or digital timepiece.
By using the translucent solar cell, the solar cell can be provided above the pointers of the analog timepiece.
The scales of a dial of an analog timepiece may be provided on the surface or back of the cell substrate.
In the timepiece as well, the translucent solar cell is disposed on the surface of a casing of the timepiece, the pointers of the analog display member and the movement for driving the pointers are disposed below the translucent solar cell in the casing, a space is created between the movement and the casing, and a transparent plate is disposed on the under face side of the timepiece, so that the timepiece can be see-through.
In this case, the cell substrate can be formed in a size so as to cover the movement and the space.
Moreover, the translucent solar cell may be disposed not only on the surface of the casing but also the back side of the casing, or the translucent solar cell may be disposed only on the back side of the casing.
Further, the casing and the movement may be coupled to each other via one or a plurality of ribs, and the movement is supported on the center side of the casing.
In this case, preferably, a conductive member for supplying the power from the translucent solar cell to the movement through the inside of the rib is disposed.
Particularly, it is preferable to construct in such a manner that the conductive portion of the cell substrate and the conductive member are connected to each other via a connection member, and this connection member has a first contact portion abutted against an output terminal of the conductive portion, and a second contact portion abutted against the conductive member.
By using such a connection member, the assembly of the solar cell is facilitated, and the solar cell and the conductive member can be connected to each other with reliability.
Preferably, at least a minute hand indicating minute(s) out of the pointers of the analog display member is extended to a position above the space created between the casing and the movement. With the configuration, the time can be known also from the back side of the timepiece.
According to the present invention, a transparent electrode film is formed on or near the cell substrate, and the transparent electrode film is connected to the ground of the unit.
Further, the transparent electrode film is formed on the side opposite to a face on which a photocell is formed of the cell substrate, the transparent electrode film is formed on a substrate face opposite to a face on which a photocell is formed of the cell substrate, or the transparent electrode film is formed on the side of a face on which a photocell is formed of the cell substrate. The transparent electrode film is a transparent thin ITO film and is grounded to the casing via the conductive member.
With the configuration, the electronic device can be protected from external environments such as static electricity built on a human body, so that a durable electronic device can be provided.